Regular Papers
Relationship between Fine Structure and Properties of Gelatinization and Retrogradation of Starches from Wheat Harvested in Japan and Canada
2011 年 59 巻 1 号 p. 1-9
詳細
2011 年 59 巻 1 号 p. 1-9
Starches and their amyloses and amylopectins were prepared from three domestic wheat cultivars (Haruyutaka, Chihokukomugi and Norin No. 61) produced in Hokkaido and from a foreign cultivar, 1CW, imported from Canada. The results of Rapid Visco Analyser and differential scanning calorimeter (DSC) showed that the patterns of gelatinization and retrogradation of these starches were different, although the amylose content of the domestic cultivars (21.0–22.2%) and 1CW (24.0%) were similar. The outer branches of the molecules of wheat amylopectins were obtained by partial hydrolysis with pullulanase and analyzed by high performance anion exchange chromatography with pulsed amperometric detection. When the degree of polymerization (DP) ranged from 9 to 11, the ratio of glucosyl chains to the total of partial hydrolysates from amylopectins was lower for all the domestic cultivars than that for 1CW, but higher than those of 1CW when DP ≥12. Subtotal of the ratio of the hydrolysates from domestic wheat amylopectins, revealed as Fraction A (Fr. A) (DP 6–12) and Fr. B1 (DP 13–24), were different from that of 1CW. A negative correlation was observed between Fr. B1 and Tp (peak temperature in DSC), whereas a positive correlation was found between Fr. A and Tp. The retrogradation properties of wheat amylopectins tended to be different, although their starches tended to have similar properties. These results suggest that small differences in outer glucosyl chain-lengths of the amylopectin molecules have a very slight influence on gelatinization, but exert a somewhat greater influence on retrogradation of wheat amylopectins and their starches.
